Scanning electron microscopes (SEMs) are employed in connection with generating high-resolution nanoscale imagery of various objects. Conventionally, an SEM emits an electron beam toward a sample to stimulate emission of secondary, Auger, and backscattered electrons from the sample. In a conventional SEM, the emitted electrons are received at a detector that outputs an indication of a total number of electrons received at the detector for each position of the electron beam on the sample. Therefore, a conventional SEM is used in connection with generating an SEM image of the sample where a pixel value of the SEM image is based only upon the total number of electrons received at the detector for a given position of the electron beam on the sample. Conventionally, an SEM does not distinguish between electrons of different energies or emission angles from the sample.
Other SEMs have been devised that image the sample by selectively passing to the detector secondary electrons that lie in a single range of electron energies. In such an SEM, electrons emitted from the sample interact with a slit that is configured to pass only those electrons within a desired sampling range of energies. However, these slit-based SEMs are unable to distinguish between electrons in different energy ranges simultaneously, as the slit must be reconfigured in order to select a different range of electron energies.